This invention seeks to improve upon the processes described in Withers U.S. Pat. No. 3,763,001 which teaches the concept of winding a fine filament of circular cross-section about a mandrel and depositing metal on and around the winding by electroplating, vapor deposition or metal spraying either after a complete layer of filament has been wound or alternatively during the winding of the filament. However, this patent acknowledges at column 3, lines 41 to 64 a problem which arises when using its claimed process, i.e. the existence of voids within the body of the composite structure due to the failure of the matrix metal to be deposited completely around the reinforcement filaments where circular cross-section filaments are being wound. Such circular filaments when wound on a surface leave an essentially wedge-shaped zone beneath the filament on each side thereof, and the matrix metal does not deposit therein, or else does not deposit at full density. The patent minimizes these voids by using very small diameter filaments and spacing them apart by at least one-half their own diameter. Later in the patent specification there is a statement at column 7 lines 34 to 55 that although larger filaments would be expected to give best results due to their greater reinforcement value, the smaller diameter filaments are necessary to be compatible with the lateral penetrating capacity, or "throwing" power, of practical deposition techniques.
Although at the time of obtaining the above patent it was believed that the void problem was solved by the use of small diameter reinforcement wire, subsequent analysis of electroplated matrices showed that it was not, and that voids remained in the recessed zones located between the surface of the previously deposited layer and the adjacent under-surfaces of the circular cross-section filaments wound thereon. The "throwing" power of electroplating solutions is of course not ideal, and therefore less metal is deposited in these recessed zones than on the remainder of the more exposed surfaces. The degree of metal deposition in the recessed zones is intimately related to the densities of the cathodic diffusion layers, i.e. the ionic boundary layers in the vicinity of the recessed zones where agitation or flow of the electrolyte is difficult to achieve for the purpose of breaking up the ionic boundary. Since the contour of the cathode surface in the recessed zones is in the form of a wedge-shaped pocket, the ionic diffusion layer will vary with position in the recess both as to density and distribution, and therefore the rate of mass transport of the depositing ions will also vary with position in the recess resulting in a non-uniform matrix growth pattern.